of iron group elements, ions must be available in quantities of, for instance, about 0.01, 0.1, 0.35, 0.8, and 1.6 ^equiv (or 0.4, 3, 10, 25, and 50 Mg) for bead diameters of 0.2, 0.4, 0.6, 0.8, and 1.0 mm, respectively.(iii) However, the method is inapplicable to ion species, such as polyelectrolytes, which may not be adsorbed by the resin in sufficient quantity to saturate the exchange capacity of the resin. Photochemical Studies of Solid Potassium Trisoxalatoferrate(III) Trihydrate by . E.